Cogeneration represents a relatively new concept in the field of generating electricity. Traditionally, electricity has been created at centralized facilities—typically through burning a fossil fuel like coal—which is then transported through an electricity grid to individual residential and commercial facilities.
Within the past several years, cogeneration systems have been developed to essentially reduce both need and reliance on these grids. More specifically, cogeneration systems employ a heat engine (typically a combustion engine) or power station located at the residential or commercial facility itself to simultaneously generate both electricity and useable heat. Most cogeneration systems use a centralized reservoir of fossil fuel to create electricity, heat running water and air and often provide energy back into the grid for credit.
Recently, there have been several forms of cogeneration systems developed for use in residential homes and smaller commercial facilities. These systems have been dubbed “mini-cogeneration” systems—due to their modest size and performance. Another common name associated with these systems is a distributed energy resource (“DER”) system.
Regardless of moniker, these systems produce usually less than 5 kWe. Instead of burning fuel to merely heat space or water, some of the energy is converted to electricity in addition to heat. This electricity can be used within the home or business or, if permitted by the grid management, sold back into the municipal electricity grid. A recent study by the Claverton Energy Research Group found that such a co-generation system offered the most cost effective means of reducing CO2 emissions—even compared to use of photovoltaics.
Apart from the energy conversation associated with mini-cogeneration systems, the technology also offers additional logistical benefits. Such cogeneration systems often offer more reliable energy solutions to residential dwellings in rural areas in which it is difficult to gain access to the grid. Alternatively, these systems offer more stable energy supplies in areas often affected by natural disasters such as hurricanes, tornadoes and earthquakes—where the downing of power lines will often lead to large periods with a lack of energy.
While there exist multiple benefits for micro-cogeneration systems, they currently possess several drawbacks. One primary drawback is that despite the creation of several forms of usable heat generated as a byproduct from the burning of fossil fuels there has been very little done to harness this usable heat for use in other home energy systems. For example, current cogeneration system designs fail to employ this usable heat to help create hot water for use within the home or commercial facility. Rather, many cogeneration systems still use archaic systems such as water heaters and related standalone water heating systems which use a separate energy source to warm water—such as electricity or gas.
Tankless (flash) water heaters (hereinafter “tankless heaters”) have offered an alternative to traditional water heaters. These tankless heaters allow on-demand sources of instantly heated water by warming a specific quantity of water—instead of storing heated water until a need arises in a home or commercial facility. Accordingly, tankless heaters allow a more regulated temperature for heated water, without risk of spending a pre-heated quantity of such water during consumption.
One problem associated with tankless water heaters is the reality that water coming into the device must be within a specific temperature range. Otherwise, it is impossible to heat the water instantly. While this does not pose an issue in tropical and subtropical areas like California, Texas, Arizona and Florida—the application and use of tankless water heaters is limited in colder climates like the Midwest and Northeast. This is primarily because the incoming water is often close to freezing during the winter months—preventing instantaneous heating.
Accordingly, there is a need in the field of micro-cogeneration systems for a system that employs usable heat to increase efficiency of other systems—including but not limited to water heating systems. Moreover, there is a need in the art of tankless heaters to allow pre-heating of water prior to entry into the tankless heater in order for these more efficient systems to be used in colder climates such as the Midwest and the Northeast—as well as other related climates. Such systems should ensure greater capture of usable heat to decrease the overall consumption of energy by cogeneration systems for residential and commercial use. Finally, such improved systems should preferably be compact, self-contained and easy to use.